NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Instrument Error
From: Fred Hebard
Date: 2005 Apr 24, 17:08 -0400
From: Fred Hebard
Date: 2005 Apr 24, 17:08 -0400
I mentioned that my sun-moon lunars were markedly inferior to other lunars. Here are some data on that. For a while, I thought I was failing to converge the objects in the center of the glass, so I bought a Russian 7x (6x ?) inverting scope with wires in the field of view, so that I could center the objects (and get greater magnification than offered by my 4x star scope). This didn't seem to help, as indicated below. In general, the sun lunars show a gap of about 1.2' to 1.4' of arc, while the star and planet lunars show no gap. The one difference that remains to be explored is that the sun lunars have much larger distances than the star lunars, so that arc eccentricities or failure to maintain the sextant in the plane of observation may be occurring. I haven't used the inverting scope very much yet, so I'm far from proficient with it. But the bias appears to persist with it, and appears to be . Date Telescope Objects Mean(clrd D) N(delarc') Mean(delarc') StdDev(delarc') 09/22/2004 4xGalilean Moon,Antares 38 2 0.1 0.38 04/18/2005 7xinverting Moon,Jupiter 58 7 0.5 0.21 04/20/2005 4xGalilean Moon,Jupiter 21 6 -0.1 0.28 10/06/2004 4xGalilean Moon,Venus 49 7 -0.2 0.26 10/07/2004 4xGalilean Moon,Venus 38 6 -1.1 0.23 09/20/2004 4xGalilean Moon,Sun 80 6 1.2 0.37 09/21/2004 4xGalilean Moon,Sun 92 6 1.3 0.49 10/05/2004 4xGalilean Moon,Sun 97 6 1.4 0.15 10/06/2004 4xGalilean Moon,Sun 87 8 1.2 0.34 10/08/2004 4xGalilean Moon,Sun 66 10 0.7 0.38 11/07/2004 4xGalilean Moon,Sun 62 6 1.7 1.28 04/16/2005 7xinverting Moon,Sun 93 6 1.4 0.15 04/17/2005 7xinverting Moon,Sun 103 8 1.2 0.24